diff --git a/nvchecker/httpclient/aiohttp_httpclient.py b/nvchecker/httpclient/aiohttp_httpclient.py
index a122571..6af4b0f 100644
--- a/nvchecker/httpclient/aiohttp_httpclient.py
+++ b/nvchecker/httpclient/aiohttp_httpclient.py
@@ -35,6 +35,7 @@ class AiohttpSession(BaseSession):
     follow_redirects: bool = True,
     params = (),
     json = None,
+    body = None,
     verify_cert: bool = True,
   ) -> Response:
     kwargs = {
@@ -47,7 +48,13 @@ class AiohttpSession(BaseSession):
 
     if proxy is not None:
       kwargs['proxy'] = proxy
-    if json is not None:
+    if body is not None:
+      # Make sure all backends have the same default encoding for post data.
+      if 'Content-Type' not in headers:
+        headers = {**headers, 'Content-Type': 'application/x-www-form-urlencoded'}
+        kwargs['headers'] = headers
+      kwargs['data'] = body.encode()
+    elif json is not None:
       kwargs['json'] = json
 
     try:
diff --git a/nvchecker/httpclient/base.py b/nvchecker/httpclient/base.py
index b9e2101..ae861f9 100644
--- a/nvchecker/httpclient/base.py
+++ b/nvchecker/httpclient/base.py
@@ -61,6 +61,7 @@ class BaseSession:
     follow_redirects: bool = True,
     params = (),
     json = None,
+    body = None,
   ) -> Response:
     t = tries.get()
     p = proxy.get()
@@ -82,6 +83,7 @@ class BaseSession:
           params = params,
           follow_redirects = follow_redirects,
           json = json,
+          body = body,
           proxy = p or None,
           verify_cert = verify,
         )
@@ -103,6 +105,7 @@ class BaseSession:
     follow_redirects: bool = True,
     params = (),
     json = None,
+    body = None,
     verify_cert: bool = True,
   ) -> Response:
     ''':meta private:'''
diff --git a/nvchecker/httpclient/httpx_httpclient.py b/nvchecker/httpclient/httpx_httpclient.py
index 7cf2345..3a17fb3 100644
--- a/nvchecker/httpclient/httpx_httpclient.py
+++ b/nvchecker/httpclient/httpx_httpclient.py
@@ -27,6 +27,7 @@ class HttpxSession(BaseSession):
     follow_redirects: bool = True,
     params = (),
     json = None,
+    body = None,
     verify_cert: bool = True,
   ) -> Response:
     client = self.clients.get((proxy, verify_cert))
@@ -40,8 +41,13 @@ class HttpxSession(BaseSession):
       self.clients[(proxy, verify_cert)] = client
 
     try:
+      if body is not None:
+        # Make sure all backends have the same default encoding for post data.
+        if 'Content-Type' not in headers:
+          headers = {**headers, 'Content-Type': 'application/x-www-form-urlencoded'}
+        body = body.encode()
       r = await client.request(
-        method, url, json = json,
+        method, url, json = json, content = body,
         headers = headers,
         allow_redirects = follow_redirects,
         params = params,
diff --git a/nvchecker/httpclient/tornado_httpclient.py b/nvchecker/httpclient/tornado_httpclient.py
index 6d5240c..ce813ff 100644
--- a/nvchecker/httpclient/tornado_httpclient.py
+++ b/nvchecker/httpclient/tornado_httpclient.py
@@ -52,6 +52,7 @@ class TornadoSession(BaseSession):
     follow_redirects: bool = True,
     params = (),
     json = None,
+    body = None,
     verify_cert: bool = True,
   ) -> Response:
     kwargs: Dict[str, Any] = {
@@ -62,7 +63,10 @@ class TornadoSession(BaseSession):
       'validate_cert': verify_cert,
     }
 
-    if json:
+    if body:
+      # By default the content type is already 'application/x-www-form-urlencoded'
+      kwargs['body'] = body
+    elif json:
       kwargs['body'] = _json.dumps(json)
     kwargs['prepare_curl_callback'] = try_use_http2